Method for producing fibrous material



May 29, 1951 c. R. AUSTIN METHOD FOR PRoDucI'NG FIBRous MATERML FiledSept. 50, 1947,

N k Jz INVENTOR.

Patented May 29, 1951 Iari-54,4226;

UNITED STATES PATENT QFFICE 554,486 METHOD FOR PRoDUoING FIBRoUsMATERIAL Chester RQAli-stinyColumbus, Ohio, assignor, by

mesne assignments; to Armstrong Cork- Company, Lancaster, Pa., a.corporation of Pennsyl- Vania Applic'at'in sebtelber so, 1947, serialNo. 776,894 4 claims. (o1. ifs-7.3)

This invention relates toI a method for produing'- fibrous material and,more particularly, to a method in which hot gasses under pressure arelused as the attenuating means for converting thetmolten material intoiibers.

The term mineral wool is used'generically throughout to include slagWool, rock wool, and glass wool, aswell as other inorganic wools.` Theterm ray/ material is used generically to include blast furnace slag,rock, glass, and other inorganic materials used in the manufacture ofmineral wool. The term molten material is used generically to includemolten wool-forming raw materials. Therterm shot as used herein refer tothe small globules of material which have not been attenuated by theattenuating blast. The Vterm short dustlike bers refers to theextremelyshort and extremely nne bers presentv in blown mineral wools and whichcreate objectionable dustiness when such wools arewhandled.

In the' manufacture of mineral wool insulation material, one of the mainproblems is the reduction of the amount of shot and dustlike shortfibrous material invariably formed when the wool is blown. It isgenerally believed that Atheshot andshort; brous material above referredto arev caused by the shattering of the molten, stream when the streamis hit by a blast of air or steam directed at an angle to the directionof travel ofthe moltenstream. Furthermore, in the convfe'ntional'methodof blowing mineral wool, the, attenuating blast is at a temperaturelower than thetemperatureof the molten stream and, therefore, has atendency to cool the molten stream at. the point of attenuation. Thiscooling of ,the stream at the point of attenuation has a definite effecton the amount of shot and1 shortdustlike bespresent'in the brous woolproduced.

In'thel manufacture of brous material from a, molten stream it has beenfound highly desirable to maintain a constant temperature throughouttheY molten streamso that the temperature atthe surface will besubstantially the sameas theV temperature in the center of the stream.This cannot be accomplished where the" molten stream is allowed to droplthrough the atr'nos'phere,A because the ambient atmosphere has a muchgreater cooling eiect on the exterior of the stream than it has on theinterior, mal;-a

more' viscous than the r interior.

cannot be' attenuated properly when the viscosity. isabove'a'certainrange, and the quality of wool ing themolteri material at the exteriormuch Experiments, have shownthat a woolforming compositionv blown frommolten streams which are allowed to fall through air clearlyjrevealsthat much of the mass of -resultingl product has not been attenuatedproperly. It is believed that thecooler, more viscous outer vsurface yofthe stream of molten material is responsible for a large percentage o fshot.

In order to overcome these -clicultiesl have devised aniethQdinwhich thehot gasses resultingirom the combustion of fuel` used in the melting ofthe raw material or assisting in keeping the rawmaterial in a; moltenstate areused toattenuatethebers by blowing the molten Slifealtbfoushan. exhaust Orifice ,ma Substantially; gas-tight f urnace. In this typeof metho ol, the attenuatingblast is at a temperature subst aritiallytheVsame as the temperature of the molten s'tream and is directed in a pathsubstantially parallel to the direction of flow of the molten stream.

Furthermore, it has been found that when attenuating i. berSgby a blastwhich is ata-temperature substantially lower than the temperature of themolten materiah the blast has a tendency to increase the viscosity ofthemateriali-ilary,madly during attenuatien and, bf

course, when the viscosity is increased to a vpoint above theattenuation ra nge,. shot or extremely.

fcfiilsfbe are farmed- ,ByHuSns a blast. at substantially the sametemperature as the temperature gt thematerial being attenuated, the beri s mainta i ned at at'tenuationAi/ SfJoS/ity forv a greater pericdpftime ande consequently, longer bers and less shot are formed.

A rinobject of thi s invention is to provide a,

metldofproducing mineral wool in which,the

fibers are exceptionally nne tough, .and v have a relatively smallamount of shot and of short dustlike bers A further object ofinventionis-to pro" vide a method oi' producing ibrous material frommolten material in which the hot gases used toconvert theraw materialtomolten material are alsolu lizedfto attenuate the ibers; the moltennr'iaterialY and hot gases Abeing vat substantially the sametemperature, thereby keeping the bers at' proper attenuating viscosityover a greater period of time in order to produce longer bers.

Another object of this invention is toV providey a' methodof producingiibrous material from molten material in which the blast used to,attenuatethe bers is; directed in a path substa'n.

tially parallel to the path of travel of the molten,

streamfratherthan atA an angle to the path of travel of 'the stream.

In order that my invention may be more readily understood, it will bedescribed in connection with the accompanying drawing in which,

Figure 1 is a longitudinal cross-sectional View of a furnace suitablefor carrying out my invention, and

Figure 2 is a plan view of the discharge end of the furnace showing theorifice through which the gas escapes and the wool is attenuated.

In the drawing, the numeral 2 designates a cylindrical furnace shellhaving a lining of insulating brick 3 and an inner layer of rammed hightemperature refractory material 4. This re-v fractory material defines acylindrical chamber 5 having a tapered end 6, said tapered end beingpartially closed by a refractory element l having a rectangular orice 8passing therethrough. It will be observed that the orifice 8 is soconstructed as to provide an enlarged opening on the inner'side of therefractory element 'I and a smaller opening on the outer side thereof.

While the drawing shows a rectangular orifice,

it will be understood, of course, that orifices of other geometricaldesigns can be utilized satisfactorily. This refractory element 'I isheld in place by a metal holding ring 9 secured Y*by bolts it to themetal plate II, which forms the front of the furnace housing. By thisarrangement, the refractory element 'I is held securely in place betweenthe refractory lining 4 of the furnace and the holding ring 9. Thisplate II is secured by means of bolts I2 to a collar I3 which is securedto the furnace housing 2. Y

The granular raw material is charged through a double-lock feedingmechanism I4 into the furnace chamber 5 through the passage I5 from anysuitable source of supplyrnot shown. With this double-lock mechanism, itis possible to feed additional raw material into the furnace chamberwhile a constant pressure is maintained within the furnace. The gas orother fuel used in the operation of the furnace is supplied underpressure from a suitable source, not shown, through the pipe IE, and theoxidant is supplied under pressure through the pipe I1 into the tube I8,which surrounds the fuel supplyV pipe I5. The fuel and oxidant are mixedin the chamber I9, and this mixture is then forced through the openingor nozzle 25 into the rear of the furnace chamber 5 in which it isignited and burned. Y Suitable adjusting Valves may be positioned in thefuel and oxidant lines to control the ratio of fuel to oxidant which, inturn, controls the temperature in the combustion chamber.

In the operation of the furnace, the granular raw material is fed intothe furnace chamber 5 through the double-locking mechanismY I4 into thedownwardly directed passage I5. A mixture of fuel and oxidant is fedinto the nozzle 2t and is burned in the rear of the furnace chamber 5.This mixture of fuel and oxidant is preferably adjusted to produce afurnace temperature of between 2200 F. and 3000 F. At this temperature,

the raw material is converted to a uid consistency and forms a pool ofmolten material 25 in the bottom of the cylindrical furnace chamber 5.Control of the fuel and oxidant supply pressures permits operation ofthe furnace under any desired pressure. The only means of escape for thegases generated by the combustion of the fuel is through the orifice 8.The characteristics of the desired fiber will determine the pressure tobe maintained in the pressure furnace and the viscosity at which themolten material is to be Y maintained. Other factors being equal, lowpressures produce coarse liber and high pressures produce fine fibers.The preferred range is between 25 to 50 pounds per square inch. However,higher or lower pressures may be used if desired. It has been foundthrough experiment that a viscosity range of 1000 Vpoises to 10 poisesis satisnace chamber.

factory for the production of mineral wool by the pressure furnacemethod, although, for the usual commercial wools, for insulatingpurposes a viscosity range of from poises to 25 poises is preferred. Asthe amount of the molten material within the furnace chamber 5 builds upto the level of the orioe B, it flows through the orice S, and theescaping gas passing through the same orice attenuates the moltenmaterial into a fine, tough, fibrous material having a low percentage ofshot and short dustlike fibers. v

In another embodiment of my invention, the furnace chamber described maybe used as a secondary heating or conditioning chamber in the productionof fibrous material from molten material. In using my invention in thistype process,

the raw material is melted in a suitable furnace or Crucible; and themolten material is fed down through the passage I5 into the furnacechamber 5. During this feeding, the burner is shut off l temporarily toprevent the pressure from impeding the ow of molten material into thefur- In this embodiment of my inention, the hot gases in the furnacechamber 5 are used to maintain or assist in maintaining the moltenmaterial in a fluid condition until atv tenuated.

In order to overcome the necessity of having the molten pool 25 build upto the level of the orifice 3, I have provided mechanism by which thefurnace 2 may be tilted in such manner that a small amount of moltenmaterial in the furnace chamber 5 may be made to now through the orifice8. To accomplish this, I lprovide a screw jack or other elevatingmechanism illustrated at 2i which is effective for raising the rear ofthe fur' nace. Since the furnace is supported on an upright member 22 bymeans of the cleat 23 and a pivot pin 24, a small amount ofmoltenmaterial in the furnace may be made to flow toward the orice end of thefurnace byV operating the screw jack ZI. It will be understood, ofcourse, in operations where it is necessary or advantageous to tilt thefurnace, it is desirable to have flexible sections such as rubber orother flexible hose in the fuel and oxidant lines.

The following is a specific example of the method of producing mineralwool by my invention: A cylindrical furnace 91/2" in diameter and 33"long, provided 'with a rectangular orice e x 1/2" in its front wall, wascharged Vwith a cold charge of granular slag to a depth of l1/2. Afterthe furnace had reached a temperature of 2500" F. and a pressure of 30pounds per square inch, additional slag was charged through thedouble-locking mechanism. An additional small amount of oxygen was fedinto the oxidant line to raise the furnace temperature to approximately2550 F. to maintain the molten material at a viscosity of approximately28 poises. The slag then started to ow and was blown from the lip of theorice.

The wool produced during this experimental run was very ne-bered, soft,and tough, containing substantially less shot and short dustlike fibersthan the wool produced by the conventional methods.

It will be clear from the above, that I have developed a new method forproducing fibrous material, in which the hot gases resulting from thecombustion of fuel in a pressure chamber are used to attenuate the bers.It will be obvious, too, that in asystem of this type, the path of theattenuating blast is parallel to the path of travel of the moltenstream, and there is, therefore, less likelihood of the stream beingshattered by a blast at a lower temperature directed at an angle to thepath of the molten stream. Also, in producing mineral wool from moltenmaterial by the above metho-d, the molten stream is at substantially thesame temperature throughout, which overcomes the difficultiesencountered by the cooling of the exterior of the molten stream when itis allowed to fall through air.

While I have illustrated and described certain preferred embodiments ofmy invention, it will be understood that the same is not limitedthereto, but may be otherwise embodied and practiced within the scope ofthe following claims,

I claim:

1. The method of producing fibrous material from a molten mass, thesteps comprising charging a mass of material capable of attenuation intoa pressure-tight combustion chamber, heating the mass in said chamber bythe combustion of a fuel-oxidant mixture to a temperature range between2200 F. and 3000 F., thereby forming a pool of molten material disposedalong the horizontal axis of the combustion chamber, tilting thecombustion chamber to allow the pool of molten material to overowthrough an exhaust orifice for the combustion gases, and attenuatingsaid mass in a substantially horizontal direction solely by theapplication thereto under pressure of the gases resulting from thecombustion of the fuel-oxidant mixture as the mass overows the pool inthe path of the escaping combustion gases.

2. The method of producing iibrous material from a molten mass, thesteps comprising charging a mass of material capable of attenuation intoa pressure-tight combustion chamber, heating the mass in said chamber bythe combustion of a fuel-oxidant mixture, thereby forming apool ofmolten material disposed along the horizontal axis of the combustionchamber, tilting the combustion chamber to allow the pool of moltenmateral to overflow through an exhaust orifice for the combustion gases,and attenuating said mass in a substantially horizontal direction solelyby the application thereto under a pressure ranging between 25 poundsper square inch and 50 pounds per square inch of the gases resultingfrom the combustion of the fuel-oxidant mixture as the mass overflowsthe pool in the path of the escaping combustion gases.

3. The method of producing fibrous material from a molten mass, thesteps comprising charging a mass of material capable of attenuation intoa pressure-tight combustion chamber, heating the mass in said chamber bythe combustion of a fuel-oxidant mixture to produce a molten mass havinga viscosity ranging between 1000 poises and 10 poises, thereby forming apool of molten material disposed along the horizontal axis of thecombustion chamber, tilting the combustion chamber to allow the pool ofmolten material to overflow through the exhaust orifice for thecombustion gases, and attenuating said mass in a substantiallyhorizontal direction solely by the application thereto under pressure ofthe combustion gases resulting from the combustion of the fuel-oxidantmixture as the mass overflows the pool in the path of the escapingcombustion gases.

4. The method of producing brous material from a molten mass, the stepscomprising charging a mass of material capable of attenuation into apressure-tight combustion chamber, heating the mass in said chamber bythe combustion of a fuel-oxidant mixture to produce a molten mass havinga viscosity ranging between poises and 25 poises, thereby forming a poolof molten material disposed along the horizontal axis of the combustionchamber, tilting the combustion chamber to allow the pool of moltenmaterial to overow through the exhaust orice for the combustion gases,and attenuating said mass in a substantially horizontal direction solelyby the application thereto under pressure of the combustion gasesresulting from the combustion of the fuel-oxidant mixture as the massoverflows the pool in the path of the escaping combustion gases.

CHESTER R. AUSTIN.

REFERENCES CITED The following references are of record in the flle ofthis patent:

UNITED STATES PATENTS Number Name Date 1,328,446 Odam Jan. 20, 19202,178,871 Drill Nov. '7, 1939 2,233,304 Bleakley Feb. 25, 1941 2,455,908Slayter Dec. 7, 1948 FOREIGN PATENTS Number Country Date 3,010 GreatBritain Oct. 22, 1908 601,354 Germany July 26, 1934

